Genome-wide association study identifies variants of GhSAD1 conferring cold tolerance in cotton

GhSAD1regulates cold stress responses in cotton through modulation of C-repeat binding factor activity, and regulation of COLD-REGULATEDgenes and ABA signalling. Cold stress is a major environmental factor affecting plant growth and development. Although some plants have developed resistance to cold stress, the molecular mechanisms underlying this process are poorly understood. Using genome-wide association mapping with 200 cotton accessions collected from different regions, we identified variations in the short chain alcohol dehydrogenase gene, GhSAD1, that responds to cold stress. Virus-induced gene silencing and overexpression in Arabidopsis revealed that GhSAD1 fulfils important roles in cold stress responses. Ectopic expression of a haploid genotype of GhSAD1 (GhSAD1(HapB)) in Arabidopsis increased cold tolerance. Silencing of GhSAD1(HapB) resulted in a decrease in abscisic acid (ABA) content. Conversely, overexpression of GhSAD1(HapB) increased ABA content. GhSAD1(HapB) regulates cold stress responses in cotton through modulation of C-repeat binding factor activity, which regulates ABA signalling. GhSAD1(HapB) induces the expression of COLD-REGULATED (COR) genes and increases the amount of metabolites associated with cold stress tolerance. Overexpression of GhSAD1(HapB) partially complements the phenotype of the Arabidopsis ABA2 mutant, aba2-1. Collectively, these findings increase our understanding of the mechanisms underlying GhSAD1-mediated cold stress responses in cotton.